NEW YORK - Semen may be a natural "upper" and its effect may be addictive, according to a recent study of sexually active college women.

The study, conducted at the State University of New York at Albany, found that women having sex without condoms were less depressed than those using them.

Researchers asked 293 undergraduate females how often they had sex, the type of contraception used and the number of days since they last had sex. Results revealed that depression levels increased with the frequency of the subjects' condom use.

"I wouldn't use the word Îaddictive,' but sex without a condom is definitely better," said Paula, a New York University graduate student who declined to give her last name. "You feel much more connected to the person you're with emotionally. Skin on skin just feels so much smoother."

Professor Gordon Gallup, who headed the research project, said although the exact cause of the antidepressant effect was not clear, it has been proven that semen is absorbed through the vaginal walls. Semen contains testosterone, estrogen and other hormones with the potential to affect mood and sexual behavior, he said.

"If the results could be proven, I suppose some attempt should be made to try to isolate and simulate the antidepressant effect," Gallup said, but added later that he was not concerned with practical applications of the study.

The study, published in the June issue of the "Archives of Sexual Behavior," has received mixed reactions.

Dr. Ira Sharlip, a urologist in San Francisco and president of the Sexual Medicine Society of North America, criticized the study in an article published on Salon.com.

"This is the kind of junk science that smears the name of honest science," Sharlip wrote.